This invention relates generally to exercise machines and more particularly to exercise machines with forced pronation or supination movement for the hands and arms.
Many athletes and non-athletes utilize weight lifting or weight training exercises to build strength and/or bulk, or to improve overall condition and appearance. Typically, weight training exercises are performed with either exercise machines or free weights, i.e, barbells with plates for incremental weight selection, dumbbells, etc. For various reasons, most exercise programs incorporate both machines and free weights in a variety of different exercise routines in order to maximize the effect of working specific muscle groups.
Free weights offer a number of advantages over exercise machines. For instance, they are relatively inexpensive in comparison to exercise machines. Free weights are also more versatile because a variety of exercises can be performed with one set of weights, whereas most exercise machines are designed for only one exercise. Even though some exercise machines accommodate more than one exercise, the cost of these machines usually increases proportionately with the number of exercises. Use of dumbbells also enables both arms to be exercised independently. Finally, dumbells are popular among many weight lifters because the lifting movements rather than being restricted to prescribed planes of motion can follow a more natural converging/diverging path.
Nevertheless, there are inherent disadvantages associated with free weights. One such disadvantage relates to safety. Most weight room instructors strongly advise against an individual working out alone, and this cautionary measure is particularly important when lifting free weights, because becoming trapped beneath a bar could easily occur in exercises such as bench press, incline or squat. There is also the danger of dropping a weight so as to cause personal injury. Also loading and unloading of heavy plates onto the ends of a bar can sometimes, through carelessness, result in an unbalanced bar that falls from its rack.
Another disadvantage associated with free weights relates to the fact that the weight resistance, or opposing force, that is exercised against is always directed vertically downward by gravity. Yet, the moment arm of the weight about the pivot point varies considerably throughout the full range of motion. This principle is explained in U.S. Pat. No. 3,998,454 with respect to a commonly performed exercise referred to as the dumbbell biceps curl. In short, during this exercise the applied moment arm about the elbow varies according to the sine of the angle of the lower arm with respect to the vertically oriented upper arm. The moment arm is greatest when the angle is 90xc2x0 and it is lowest when the angle is 180xc2x0 and 0xc2x0.
If the resistance capabilities of the muscles of the human body matched this moment arm, the degree of difficulty experienced by the exerciser would be uniform, or balanced, throughout the entire range of motion. However, as reported in U.S. Pat. No. 3,998,454, the strength generated by the human muscles during this exercise is not in fact xe2x80x9cbalancedxe2x80x9d throughout the range of motion, and there are some xe2x80x9csticking pointsxe2x80x9d of increased difficulty. As a result, maximum benefits are not achieved when performing a biceps curl with a dumbbell.
The pullover machine disclosed in U.S. Pat. No. 3,998,454 utilizes an eccentric cam to vary weight resistance over the range of motion for the muscles utilized in a pullover maneuver. Over the years, for various muscle groups, a number of these cam and chain machines have been designed in an attempt to match a resistance variation through a range of motion with the natural strength curve for a particular muscle group associated with the range of motion. An improvement over the use of free weights has been achieved, according to the extent that these machines succeed in varying the exercise resistance to match an appropriate strength curve.
Some exercise devices in the prior art allow the handles gripped by the user to pivot freely while moving through the range of motion for an exercise. Some others, specifically Fulks U.S. Pat. No. 5,769,757, force a supination or pronation movement in the hands and forearms. There are however, no existing exercise machines that truly emulate the feel and effect of exercising with dumbbells.
Therefore, the object of the present inventions is to provide exercise machines with the safety not inherent to the use of free weights, while emulating the feel and effect of exercising with dumbbells. A second object is that the exercise machines of the present invention be configured to guide lifting movements along a natural, converging or diverging path, while permitting natural pronation or supination movements. A third object of the present inventions is to provide the aforementioned characteristics together with a capability for varying the exercise resistance to match an appropriate strength curve.
In accordance with a preferred embodiment of the present inventions, herein is disclosed an exercise device with free pronation or supination movement of the hands and arms in conjunction with the standard range of motion for a specified exercise. The device comprises a base frame and a centrally mounted seat. The seat is bisected by a vertical plane that extends through the middle of the frame so that the device has two sides that are mirror images with respect to the vertical mid-plane.
A pair of levers are pivotally attached to the frame for rotation about an axis A1. In an embodiment configured for use in xe2x80x9cbenchxe2x80x9d pressing or rowing type exercises, the user sits above axis A1 and the levers extend in a generally upward direction. A member may be attached between the levers so as to require the levers to pivot in tandem about an axis of rotation A1 or, in another embodiment, the levers may be mounted to pivot separately.
Pivotally connected to the distal end of each lever is a handle extension. This connection allows pivotal movement of the handle extension about a second axis of rotation A2 oriented in a substantially perpendicular relationship to axis A1.
An off-set linkage rod connected between the handle extension and the frame by means of ball and socket connectors causes the handle extensions to rotate about axes A2 so as to converge and diverge as the levers rotate about axis A1. Handles are pivotally mounted at the distal end of each handle extension, with each of the pivotal axes A3 lying substantially in a plane defined by the associated axis A2 and the longitudinal centerline of the handle extension. The handles are free to rotate about axes A3 so as to allow natural pronation and supination throughout the range of movement. Thus, doing a given exercise on a device embodying the present inventions has much the same feel and is functionally equivalent to the same exercise with dumb bells.
In operation, as force is applied by the exerciser to the handles, the levers (of a press machine) pivot forward about axis A1. As the levers pivot about axis A1, the handle extensions are forced to pivot in a predetermined fixed relationship about axis A2 so as to converge. The hand and forearm of the exerciser would undergo a pronation movement except that the grip handle is allowed to pivot about axis A3 as the lever is pivoted about the axis A1. The hand and forearm move forward and inward, along a converging path, as the lever is pivoted, but pronate or supinate only as desired by, or comfortable to, the exerciser.
An alternate embodiment, as might be used for a curling machine, is basically the same in principle, except that axis A1 is preferably located behind the user""s back and the lever and handle extension members extend more or less horizontally from axis A1 on either side of the user.